SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1138e81dd2f2be69efa736b4164a6e43dc6cfc81d91598359f9d7e926620d2d0' 
  AND token = 'jqej1aH2Nm+jzoJzk+PM4h0mlTiHG8aqNrNurY1I3rM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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