SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de05cdb8afb5373ccd3486cb26ec5513f26721552734e5408485b886ba5d5e81' 
  AND token = 'k4pov1NlRTTxH/gKafqbGvsSAfZwfWQWfmLzinJBFvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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