SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '037212cf63c9841d7102fa81a11592be8a62a15830ab04fb078bd99255437bcd' 
  AND token = 'PKNpeFl3RgVm4a2Ew+7nKZBXw4NbWK1/GlEIyZu4dmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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