SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '1891d24babf63da321293d87611bfb39813bcaf341de16fa9b1217eac9a512f9' 
  AND token = '53+YNLG52ugcHoXDJtGIZ+hQhOg6sOWQ+mVlvT34mis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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