SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94f51b4ab82cd0fedaedf1383b70bbe944ec160fcee0eaa62431eaec1faf6e21' 
  AND token = 'YTeNdaXd3vGCTSEe+azJvgau2SFoc1/1AXCHh/qNwMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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