SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '78853d9a89abb26407546f367c5ab3b391d7408a766e2c4b49394e268183f1a3' 
  AND token = 'K81x5uRjGHC/D9otDLhHOREYCbyba4mI8yf+qwTZkVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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