SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bf20618f72431e091a52464113ca1034f5d32e20ee3c7c25f32c998c784da26' 
  AND token = 'SnsAjl3SHuD3jPOrZipyERa2XmXStcQZn/5lAwARxd4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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