SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8ee64110f1ffdc831276beee5dfc2392af50f37c4a1758c9e4afe7fddeca36f' 
  AND token = 'qaGqMbBDpaHJhWZ4cE/oLKexHBnRt7c9M0e3hhX4gXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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