SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e0ec4306b937623d2fc17df3da3cc8c878721a2495c8daa21bc7aa9a0cf9fd9' 
  AND token = 'Jmw5ZdxXH9tgXsQpPcY4TS+6/NVWUMMqAwQuYEajQlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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