SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '814561fddab911e6bfdba78e14cadd267d767e2ac7be4aaed660b0463fd7866f' 
  AND token = 'nAN4asECGs/N9djI8rwUY6DOmc05JDLTKhY0KWeNpP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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