SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d2bc4f9b12b656d3774940f299ab4300fd0a8cddfb138f6115c840d36ca0488' 
  AND token = 'KxpPIEPz6NLlFWqW0pCOnpLdNrhzKbD9HgFlmLNeaZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}