SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a99fb694904ed0d61a30fb01b97f9c67d1ed842f645ee8e5e24a7ab8dd8b428b' 
  AND token = 'sMpN5+bP+d0NVBQpQnAbQ+j9c7qbPLTipCSoUlnTDTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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