SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '468f2b799350ba41efc987a27486e242c84488e2975e32b06c838650850da87a' 
  AND token = 'ruUV12XDQ+E8g0HMjXtfR/mEddhPNxtBNgOJSaHznBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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