SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a82f8dccc089353baf9080669ab2d81d8d7bb33fbfd39e590a66f447dc61f16d' 
  AND token = 'friQKw3/027m4vWd1S5xat6GadgavvuZEIEeLnWdh3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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