SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ccc1b3246e9aa915929745fcdf8551ee2830278cfa33861b3068db5489e83d' 
  AND token = 'hdrgJM3PYIBQQu/vEq73yG96srB9w2BZ9InAlS6kza8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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