SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fbf137175b811f9ea47a3608efbd5b4f96aada058fcfaaa0ea7f39439714635' 
  AND token = 'X+UOF288pFJfc6ejx+LGjg1Csw30U4OLxqWvSReEoaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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