SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fdd43332a4538bfb7136e62fc257cac1024b74fe4c8f204b08a282009e23d9a' 
  AND token = 'dCnfthik2bPNEAHd2GwXqZ+VuwuFbcFQyWYHuuCrkaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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