SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7550f1df513c7fd627d576feb27010353a7e02e191f462ffffe8820385b0405f' 
  AND token = '3icQShnv+NPjkopbbW/xOWTFfPYY6eCs201J58Ycrj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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