SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79f715ee1f33c159b89888bc35f1d6dada8669845c5a42e7bbe58dda3c28142b' 
  AND token = '5xPuBeU1V+DVdPBOl2Fltw0CkGVqFegh2TqiRgzmXqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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