SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c91f10207fccd578403c632e7bae2cbd3b7bcc6161539fa570a98d3663ffb98' 
  AND token = '8qdhunC04THy5EALIIcVfSg+HAFkFv/sxaHSEQO1ngo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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