SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f4557fdf8c5d510b27697c4668829b943f69af1fbb006578016a722812236d4' 
  AND token = 'K+JhqhXTsfRyY3vdNQPexIbYCZdoq3UUg9wAsS5WKlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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