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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18136556dcf2d345da8dd5bc085c9c8f61dd4b46ab37c2e250e94f4a20e4348' 
  AND token = 'DLcDNKEOVaJwEOA0G40ORl2QGRQwzzZPCOJErswyCfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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