SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c46b00ebe1ce197142b40159089357ad3a5d827edf42d78c10759867970647e' 
  AND token = 'nM42ehNO0fpjcnXh5XbrYbsM4BkbWZ3TmqYTwRNWkCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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