SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efb1a9192c6050aa2b071028ae5eaec71774d3d11424170499002e5bb04a45c2' 
  AND token = 'asi3ciGSpArP6qd/18jwlksUAgfPl+xCB/lkCcykS3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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