SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84c6af51053ea7bb37f97b83523b4b5f30503a780ead2847799e6890c08da0ca' 
  AND token = '5DyUXxWMk5cNgus/coD1vXCJqwZfXyKcJWGdBDfxAY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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