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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a8cb116f5dca2a73a4d6931ce6bd17f0a0705301c27dd37d3e85e376e4de5a' 
  AND token = 'ZxJyAxIvp0IALnWkj6pXrVs8lP6ewYpRT3+4uc0/pmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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