SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20ddf8aa7792d6e4217a5b9d8e8b7eadcf3e30110482623ec842d04e29c9c5ee' 
  AND token = 'jpiOBZw4lKiPYvfIPzyskIs4LEjqtdn+qvcrNbBtGVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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