SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7dac001cc99b44fd0f96530a29b6f539e2735a2b73fe762ecc0b4b8c068cb020' 
  AND token = 'l/BVR5GZmMc3iPTXSZkXyqx/o3VayvUcMB/VYD++gts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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