SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '78b169cc687be079dac175c170c5c4e72973ca744be0410f84d6803c137ef112' 
  AND token = 'mTwxp5qOkUrWxkJdhRuQFkTi5cNsNqd1Ndu7mcXVVkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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