SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6d79f3d2103e34bb993a2593859651caa9aa93cb5aaf6c2983e8a88edb3e5d14' 
  AND token = 'b//xb7thgwJsL9OOdiKPWBM2WN8XWyOKpgxhk4aVzwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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