SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b81add778b704c92e73227e7f0bc5e667b512b984dc9da8251224efb185a470' 
  AND token = 'TQIauFNqd0yBQeBua78zA8phbJdvnmNOgzN+0XuRh4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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