SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab16c7a793c412007f8f16845800c3372c54f3c1f83e86e185434e0886bc765' 
  AND token = 'AGw7IIajrnoj4x5ZiQHuWTLktr6XEv3hOzPPXIhNjcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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