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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c68a9d3a7e7c4cde07a7ea2e0eb4542c81dbfa688d48b19c694ea6db9b2a6d' 
  AND token = 'dr5JcwmsY+HLapXKDPusHEfHYBA5IonLWkYXj6T78iU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}