SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '38cfa549218e0f7bb76f0d9b7c53e00a5d09db3c56440e23bac32cdac6baf686' 
  AND token = '67L96UaEUiSk+I22WzUFA0FKYOOZVWINpMp0OTplusc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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