SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '644b9323ba5cfbbd58e5861244306aa32ad29dcbc7936875a65c660f73716e67' 
  AND token = 'xtr0SX3tHxswLcnmiUqVvrTOznht9sJy78Y7uqZSgFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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