SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4e31bb0a3c55c527a44a978c952758959eab7aeba3444f6eb566c1e5664d799' 
  AND token = 'SxZbY+kTpjZZVu0N3+WdgJYR5tnSDStZCicm/muUMQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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