SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe4452fb866cf79e9988f3ea0de83742b5ec5e00f0aa34e7aaa9fbb8ffd71cc2' 
  AND token = 'zzfulJZSH3kQbSZk3OM1AEacTjh6fjgcoQZoGVRZ4L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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