SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4136abcfc93cea1f92ae72028234fe776fa04f842e42385abba36f7273167e9' 
  AND token = 'IsP4SGgsYOWDMP2TQFmFfKBsNhSrGMLxBpZjfkHskds=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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