SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c020653f2578a3160ab34ad5d6dd6d5378c8bfa1c16b4d97f2dff9a85b0cb6f4' 
  AND token = 'Zcq+luIgOk4lRNVtbsumWBOZZgeaVCSmwYVhEO1LNiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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