SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50171c24489f91a146b87b7c2ab47e98f9bb337963056f03db803cce8f44954a' 
  AND token = 'AyOB9fA7XnAUFQj3ZpLLFvFxA5lXChqDswG1jAbucZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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