SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad0c98eb738a880a4cfafd336110c9241bcffcea3387bc35b2c8d4a37ef99754' 
  AND token = 'z3tfr/JiAreUOKb4oY8YA00rIMKxYsha+UXjwXu74WU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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