SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b9a6e5b4d9681a99bbada5b3e201df7f38d5d84006e577d5403a9e764ea476e' 
  AND token = 'loLHbSlE/kLb7aUnO+po9NEJFVRDLqQHrfSDKbABRAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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