SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e03028b511c8b5babdbc2648c0950221a78eed0285e8d03aebe5e09045d70a4f' 
  AND token = '28beThz8wgAv0RmY/14fgrMpWmU7ANMFiv05dYIhRU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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