SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7993dcdf360a1201b6ecfbd58f03aed9225a1c00d2ba16a2f4b9e426839443ca' 
  AND token = '9ClRqOtsmQ1BMFlvzaUVtO+pJFz6wzNK4xqBCVbX/tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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