SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28a1d28323a0e790f8ef882bc67725db54899b184f6b525ace8ac3c27196b798' 
  AND token = 'ZUb03/QRi64ONlzrLthbMJTsZLsLMjXapWGmPpLEZxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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