SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57b41dbf0a3590c758eaaecd75e6f9cc5bad131c38aed55dc81f4e0a09338e2' 
  AND token = 'jkhxKVx/O1z/ZAci09YaLegGZEKeJ8ZgkGNpkcD5VjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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