SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ce9c733fdc48d48b7a4764e9619f5684d42af848965aea2fd11d21fe32e401' 
  AND token = '9hEzB3NtuYUF9BWvbSvA2lSdZV51VHBZxlnVpQBRy3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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