SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cb81e70705eb3962f4493a131e8cd25decb69a91ebf9a967f8c752e31fdffaf' 
  AND token = 'up2RHKQBBPUwJ4HZQtIXp3JQq7/jZadM9jKsLEhcokY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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