SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52ee61218a3665cd7d313f630df1fd02eea51e42acec887de37107a282642074' 
  AND token = 'DHzfV2J11XtfsHAsS6BoTD7sCXcSOqOGTAbMAPDP9vA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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