SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1688e4e508081bb224e8516d518d9cc425a33152f88e3b77f6bad548ae0f9ce' 
  AND token = 'CvhJtwC56b9/8lpUlfz+KOU4EA2JsKOIP0wF/TVKGSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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