SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518a070d0b7da121de4d0ecb24b2241ecdaf1dfd50e2f840c9bd3250f864bcd0' 
  AND token = 'pTajdPxdbtoVi3Y9FM2q/bmcahNvfTnTKLK3KtNRTsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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