SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16823d8cf8097677d37cf4ceb16a8fe531ba610accdd9d604dfc570e89d3ff5e' 
  AND token = 'PMVXyeQIIOznpLvF7CKWu2ITbqZI9EVGwGgUyDxv5p4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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