SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857ce98561385e7cae7546061ab5f1703e1ce30418066f3c33fe61918992d53a' 
  AND token = 'RkJkwe2Txc1+hx96tN56uoKLGa6Lq2I95kfkZXsK7og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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