SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8884083ee0c8c7bae86092eef30a12b091517fd2148722a73cb71e05fa256094' 
  AND token = 'gTY+rzpP0f7NoqLx1yH0hm+wsrlhaLclRNghh1S+lhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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