SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6fd48b8612bbdc43b7c61e3b72cd245145471a609d7597f3d8aae966d460ea12' 
  AND token = 'KEYEpPdy5Ny8vCOLHaf9cc1GphiICYt+CXfGfTaL6bE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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