SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac52909d7fe2b57c8d6cd74ebec3dc88064dd44e8951031a34160c818850a284' 
  AND token = 'gxnpdAcUJBg0JJe60DF4QvX6hzFTE0vkvIDjuCRPLmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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