SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877510f02ac4dabc33f631ed4e7798e27e3775e59fd44fd8c0380252a75fa34a' 
  AND token = 'r68hQ+704J08eJ4mu+CVWQXHz8LozNPpN4ELS6dNtlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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