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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c88f18dca9b6cca395822af6b3f2c6a8adaf2e75f27999971408ad8f88cdd4c4' 
  AND token = 'RCh0jbARPiu5tHTBYkrwS3wy3UtbGIlMJHDPg2KM2cE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}