SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27137b5ce3462352bad55cae461262c51e1e3e3fb45cb494ba769b5bcd405eb8' 
  AND token = '4nKkzgTPjWdLTNhzWcoajSo0dW40xvLMgo5cXExkYYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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