SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bc89e0a9a3a140de7ea5192fb5d80d9e819c205c0bdc96caf6669b5b8c3557f' 
  AND token = 'mgU8/v3PAoSUQFAMTb+2iZ0g2weHzkpeZVEXhj3T5xg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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