SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71df1b59d06a6dfdc280150cdb5e93cf4591a773dc31f078a3383ffcbc96c4af' 
  AND token = 'I2eZ7ebjTngT016pknpQ+QWn+8ewynfpmb3gSqShgvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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