SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'befe71098130ce97a1f523e4a75a6cdd48e853694facb91a7aa8a4e7321eb733' 
  AND token = 'Y7gIrOtc+Gu5Dw/Vs4qhMzRP1xdn4glyFEW5CtG69vY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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