SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e51e38fbfffbd2ca8330ac14a664e050789a21f8385026240641f3687aec815' 
  AND token = '7TBFJVEpfJU6UKT4txV/845lBCoxaIstdUZ/I9Na/7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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