SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c41333aced13bf001743f134bbe5bb6d6cb28c184f61fe82077b4d77be73ba' 
  AND token = 'cT3rMxpRN9Ze3RLR9KOLYpbXDzoHsW0sxDXyZEiz0hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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