SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c3c71660e70fd44930c81fc1a716e8df11331b1fee1594ee5151b2c58acd3a2' 
  AND token = 'NoCX+FMKcpc48FK3rJFCEbzBoLnbTP3UgBhtbEKCUT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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