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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '590f5fa9cfe8ad67f09fe1856f2bfed71a8c603763b488b1d90a7b8efc297a26' 
  AND token = '91J0n7XRfjaEl8vF1lbjDEeJ/fpf0f/hFyoqqtHQi3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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