SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8e271c32a822a964676880b32057b4887ead7350f80f3ad82781f74d9857b1c' 
  AND token = '9zEmX3fHSyqiUgyNk40si1qVQLMQTO3Ysc5i3IpQD+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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