SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ad4dbb649b5798536401bb3f851b14b661305b0e66ae132158a5e870250a700' 
  AND token = 't0/NvUKqYmufCX5EjTsXxpqoLSeUJLdhX+uugn73am0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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