SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eaf429321e9adb1539c681fa6add28ecbce1950c4af28468fe23479d61ddb471' 
  AND token = '0XJwgkakmTZzYXvHRvf5ieymZJPdiJitr5EJO23Khr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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