SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5c39ec557bf7274c3a92cf2298bfcddb8b16ebafe52bdf4901d60c7de4bb42e' 
  AND token = 'rt0kblrJ+vkBCLtwar0QSqZ78bCm+6ivSGaNIThsMwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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