SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '452ef1596ef3957338987b9d1aedc555d7b77d9a91be3b920745926bce192b75' 
  AND token = 'khkMftRCNHVd58pwn+I20MG5pSKHOQe71sZlq3+nyCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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