SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79b91292f6713a2f9a65d12965c34f9402c57796b5a20565d08954cf487f40b8' 
  AND token = 'zPAiDO1v1ALClSJt62KaGJSFWLw9nOWvCmPcyhYZ6f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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